Oxygen isotopic compositions of seawater in the Maxwell Bay of King George Island, West Antarctica

Abstract

This paper reports on the oxygen isotope characteristics of seawater in the Maxwell Bay and Marian Cove of King George Island, Antarctica, and discusses the formation and mixing of water masses. In a transect across the Maxwell Bay, distinct water masses can be identified based on the vertical distribution of temperature, salinity, and δ18O values. Surface layer of warmer, less saline and lower δ18O water (i.e., Surface Water) overlies colder, more saline and higher δ18O subsurface water mass (i.e., Winter Water) in the Maxwell Bay. A positive correlation between δ18O and salinity suggests that water masses are formed through mixing of water from the tributaries (e.g., Marian Cove) and partly from the Bransfield Strait. In the Marian Cove, horizontal distribution of δ18O clearly shows the dispersal patterns of low δ18O meltwater. Based on the relationship between δ18O and salinity, large amounts of freshwater (δ18O=−44%.) are inferred to have been drained from the melting glaciers in the nearby coastal region during the austral summer. The oxygen isotopic composition of seawater in the Maxwell Bay can, thus, be used as a potential tracer for the formation and mixing of water masses.